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#11
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polarity of power cord - gateway fpd1520
"William Sommerwerck" wrote in message . .. On the monitor it should be marked or say something in the manual. "The Lady from Philadelphia" forgot the obvious. Power sockets almost always have their polarity marked. I've certainly seen plenty of them that didn't though. |
#12
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polarity of power cord - gateway fpd1520
On 3ÔÂ28ÈÕ, ÏÂÎç4ʱ45·Ö, zirath wrote:
We recently got a gateway fpd1520 (15" lcd flatscreen) monitor from ebay. It didn't have a power cord. It says it's a 12v dc 2.5a but it doesn't give the polarity. A person from gateway said he thought it wouldn't hurt the monitor if it got plugged in backwards but I'd rather not try it. Would appreciate any help. Do you want access to China's massive pool of electronic manufacturers... but lack the time to contact suppliers, negotiate contracts, arrange shipping or monitor product quality? Don't worry - Let seriouswholesale deal with all that for you. *Check out the huge range of Gadgets, MP3 / MP4 Players, Car DVD / Audio, and Computer Accessories now by visiting the online wholesale catalog at seriouswholesale. com You'll have peace of mind thanks to the seriouswholesale Quality Control, 12-month Warranty on all products, and easy secure payment by credit card through Paypal. Selling on eBay or your own online store? Send products direct from our warehouse to your customers using our unique drop-shipping service. You can profit by selling hundreds of different products, without holding any of your own inventory! Any questions you have will be answered by the seriouswholesale English-speaking customer support team... Their aim is to make your China electronics importing business easier to run than ever before. Welcome to http://www.seriouswholesale.com. seriouswholesale - Buy from the source, profit without the hassle. - 12 Months Warranty - No minimum order restrictions - Drop-shipping with no additional fee - Pay by safely by PayPal seriouswholesale Wholesale Co., Ltd.: Chinas original and best online electronics wholesaler & drop-shipper: seriouswholesale. com |
#13
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polarity of power cord - gateway fpd1520
zirath wrote:
We recently got a gateway fpd1520 (15" lcd flatscreen) monitor from ebay. It didn't have a power cord. It says it's a 12v dc 2.5a but it doesn't give the polarity. A person from gateway said he thought it wouldn't hurt the monitor if it got plugged in backwards but I'd rather not try it. Would appreciate any help. Thanks to everyone for your help. |
#14
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polarity of power cord - gateway fpd1520
In ,
Arfa Daily typed on Fri, 28 Mar 2008 16:07:57 GMT: "BillW50" wrote in message . com... In , Arfa Daily typed on Fri, 28 Mar 2008 12:52:58 GMT: [...] As for a transistor radio that uses PNP transistors, I haven't seen one that uses transistors at all for many years, let alone PNP ones, so I think you might be struggling to fit that into my "modern" category, also. Well Arfa... they still use transistors (both NPN and PNP types) in modern equipment. The reason you don't see them anymore is do to the magic of minturization. But they are still there, just neatly packaged into what is known today as the intergrated circuit (IC chip). And I though I was pedantic !! Yes, of course ICs contain transistors, and yes, I would accept that some of them may be PNP types, depending on block function within the IC, but I don't think, with the best will in the world, that this is the level of transistor existence that William was referring to with his "transistor radio using PNP transistors" scenario. In any event, in the case of an IC taking a single polarity rail, it is irrelevant whether the transistors inside are NPN or PNP or FETs or whatever. PNP transistors are just used 'upside down', as are discrete PNP transistors when used in any piece of single polarity rail equipment. The ground is still (typically for //modern// equipment) the "-" side of the power supply / battery. Anyway, this is getting out of hand. The OP aked a simple question, and I gave a simple answer. This afternoon, I was in a friend's computer repair shop. Bear in mind that he deals with monitors of all types and makes on a daily basis. I asked him how he would go about determining the polarity of such a monitor, and he said that he would stick one side of his ohm meter on one of the D connector locking screws, and the other on each pin of the DC connector. When he found the pin that read short to the connector locking screw, it was his contention that he would have identified the "-" side of the power supply. So that's pretty much exactly what I said. He also frowned and shook his head, and said that he couldn't remember how many years it had been since he had seen a DC connector that had the pin as the "-". Which is also pretty much what I said ... Arfa That would be okay if it were a negative ground system. But like what William Sommerwerck mentioned, we don't know that. The way I would do it is to ohm the the power in. And the lower resistance would be the correct polarity. Although you would need another meter to read the polarity of the ohm meter. As they are not standardized on multimeters. You could also use a diode (or LED) to learn of the polarity of the meter as well. -- Bill |
#15
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polarity of power cord - gateway fpd1520
"BillW50" wrote in message . com... In , Arfa Daily typed on Fri, 28 Mar 2008 16:07:57 GMT: "BillW50" wrote in message . com... In , Arfa Daily typed on Fri, 28 Mar 2008 12:52:58 GMT: [...] As for a transistor radio that uses PNP transistors, I haven't seen one that uses transistors at all for many years, let alone PNP ones, so I think you might be struggling to fit that into my "modern" category, also. Well Arfa... they still use transistors (both NPN and PNP types) in modern equipment. The reason you don't see them anymore is do to the magic of minturization. But they are still there, just neatly packaged into what is known today as the intergrated circuit (IC chip). And I though I was pedantic !! Yes, of course ICs contain transistors, and yes, I would accept that some of them may be PNP types, depending on block function within the IC, but I don't think, with the best will in the world, that this is the level of transistor existence that William was referring to with his "transistor radio using PNP transistors" scenario. In any event, in the case of an IC taking a single polarity rail, it is irrelevant whether the transistors inside are NPN or PNP or FETs or whatever. PNP transistors are just used 'upside down', as are discrete PNP transistors when used in any piece of single polarity rail equipment. The ground is still (typically for //modern// equipment) the "-" side of the power supply / battery. Anyway, this is getting out of hand. The OP aked a simple question, and I gave a simple answer. This afternoon, I was in a friend's computer repair shop. Bear in mind that he deals with monitors of all types and makes on a daily basis. I asked him how he would go about determining the polarity of such a monitor, and he said that he would stick one side of his ohm meter on one of the D connector locking screws, and the other on each pin of the DC connector. When he found the pin that read short to the connector locking screw, it was his contention that he would have identified the "-" side of the power supply. So that's pretty much exactly what I said. He also frowned and shook his head, and said that he couldn't remember how many years it had been since he had seen a DC connector that had the pin as the "-". Which is also pretty much what I said ... Arfa That would be okay if it were a negative ground system. But like what William Sommerwerck mentioned, we don't know that. The way I would do it is to ohm the the power in. And the lower resistance would be the correct polarity. Although you would need another meter to read the polarity of the ohm meter. As they are not standardized on multimeters. You could also use a diode (or LED) to learn of the polarity of the meter as well. -- Bill JHC !!! Do you not understand the word "modern" ? Do you not understand the phrase "... deals with monitors of all types on a daily basis" ? I repair this stuff all day every day for a living. I have done for over 35 years. I cannot remember the last time I saw a piece of kit of any description, which employed a positive ground. My friend, who owns a computer repair shop, and has done for many years, cannot remember the last time - if ever - that he saw a monitor with an external power supply, that was not negative ground with the connector sleeve as the negative connection. With so much interconnectivity between household items now, there has had to be a degree of standardisation on this issue, and it has evolved through a general concensus amongst manufacturers, that negative ground will be the convention. As for your method of determining polarity, it makes no sense at all, unless you are assuming a series diode, which is quite unlikely in most modern kit, as it represents a waste of power due to its forward voltage drop. It may even have a shunt protection diode, in which case, your 'test' will ensure that the polarity is determined INcorrectly. Even if the device did have a series diode, depending on where the supply first goes, there is still no guarantee that there will be any reading at all on a standard multimeter on ohms. If there is not any diode - series or shunt - any reading of ohms obtained across the input socket, is unlikely to reveal anything meaningful. What is your experience in fault-finding, I wonder, to have caused you to have formulated such a bizarre method, and believe that it would uncategorically give you a correct result ? Arfa |
#16
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polarity of power cord - gateway fpd1520
Arfa Daily wrote: JHC !!! Do you not understand the word "modern" ? Do you not understand the phrase "... deals with monitors of all types on a daily basis" ? I repair this stuff all day every day for a living. I have done for over 35 years. I cannot remember the last time I saw a piece of kit of any description, which employed a positive ground. My friend, who owns a computer repair shop, and has done for many years, cannot remember the last time - if ever - that he saw a monitor with an external power supply, that was not negative ground with the connector sleeve as the negative connection. With so much interconnectivity between household items now, there has had to be a degree of standardisation on this issue, and it has evolved through a general concensus amongst manufacturers, that negative ground will be the convention. As for your method of determining polarity, it makes no sense at all, unless you are assuming a series diode, which is quite unlikely in most modern kit, as it represents a waste of power due to its forward voltage drop. It may even have a shunt protection diode, in which case, your 'test' will ensure that the polarity is determined INcorrectly. Even if the device did have a series diode, depending on where the supply first goes, there is still no guarantee that there will be any reading at all on a standard multimeter on ohms. If there is not any diode - series or shunt - any reading of ohms obtained across the input socket, is unlikely to reveal anything meaningful. What is your experience in fault-finding, I wonder, to have caused you to have formulated such a bizarre method, and believe that it would uncategorically give you a correct result ? I guess that no one bothered to check out the link I posted to a replacement supply that not only shows it to be center positive, but it tells you which coaxial power plug you need. -- aioe.org is home to cowards and terrorists Add this line to your news proxy nfilter.dat file * drop Path:*aioe.org!not-for-mail to drop all aioe.org traffic. http://improve-usenet.org/index.html |
#17
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polarity of power cord - gateway fpd1520
In ,
Arfa Daily typed on Sun, 30 Mar 2008 14:23:08 GMT: "BillW50" wrote in message . com... In , Arfa Daily typed on Fri, 28 Mar 2008 16:07:57 GMT: "BillW50" wrote in message . com... In , Arfa Daily typed on Fri, 28 Mar 2008 12:52:58 GMT: [...] As for a transistor radio that uses PNP transistors, I haven't seen one that uses transistors at all for many years, let alone PNP ones, so I think you might be struggling to fit that into my "modern" category, also. Well Arfa... they still use transistors (both NPN and PNP types) in modern equipment. The reason you don't see them anymore is do to the magic of minturization. But they are still there, just neatly packaged into what is known today as the intergrated circuit (IC chip). And I though I was pedantic !! Yes, of course ICs contain transistors, and yes, I would accept that some of them may be PNP types, depending on block function within the IC, but I don't think, with the best will in the world, that this is the level of transistor existence that William was referring to with his "transistor radio using PNP transistors" scenario. In any event, in the case of an IC taking a single polarity rail, it is irrelevant whether the transistors inside are NPN or PNP or FETs or whatever. PNP transistors are just used 'upside down', as are discrete PNP transistors when used in any piece of single polarity rail equipment. The ground is still (typically for //modern// equipment) the "-" side of the power supply / battery. Anyway, this is getting out of hand. The OP aked a simple question, and I gave a simple answer. This afternoon, I was in a friend's computer repair shop. Bear in mind that he deals with monitors of all types and makes on a daily basis. I asked him how he would go about determining the polarity of such a monitor, and he said that he would stick one side of his ohm meter on one of the D connector locking screws, and the other on each pin of the DC connector. When he found the pin that read short to the connector locking screw, it was his contention that he would have identified the "-" side of the power supply. So that's pretty much exactly what I said. He also frowned and shook his head, and said that he couldn't remember how many years it had been since he had seen a DC connector that had the pin as the "-". Which is also pretty much what I said ... Arfa That would be okay if it were a negative ground system. But like what William Sommerwerck mentioned, we don't know that. The way I would do it is to ohm the the power in. And the lower resistance would be the correct polarity. Although you would need another meter to read the polarity of the ohm meter. As they are not standardized on multimeters. You could also use a diode (or LED) to learn of the polarity of the meter as well. -- Bill JHC !!! Do you not understand the word "modern" ? Do you not understand the phrase "... deals with monitors of all types on a daily basis" ? I repair this stuff all day every day for a living. I have done for over 35 years. I cannot remember the last time I saw a piece of kit of any description, which employed a positive ground. My friend, who owns a computer repair shop, and has done for many years, cannot remember the last time - if ever - that he saw a monitor with an external power supply, that was not negative ground with the connector sleeve as the negative connection. With so much interconnectivity between household items now, there has had to be a degree of standardisation on this issue, and it has evolved through a general concensus amongst manufacturers, that negative ground will be the convention. As for your method of determining polarity, it makes no sense at all, unless you are assuming a series diode, which is quite unlikely in most modern kit, as it represents a waste of power due to its forward voltage drop. It may even have a shunt protection diode, in which case, your 'test' will ensure that the polarity is determined INcorrectly. Even if the device did have a series diode, depending on where the supply first goes, there is still no guarantee that there will be any reading at all on a standard multimeter on ohms. If there is not any diode - series or shunt - any reading of ohms obtained across the input socket, is unlikely to reveal anything meaningful. What is your experience in fault-finding, I wonder, to have caused you to have formulated such a bizarre method, and believe that it would uncategorically give you a correct result ? Arfa Actually being an electrical engineer for 35 years, I could careless how long your friend has been repairing computers. And the reason why the ohm meter works is because all of the curcuits are in parallel with the supply. Thus you will get a lower reading when the polarity is correct. And you will get a higher reading when it is not correct. Thus as all of the circuits are reversed biased. Whether or not all manufactures use negative ground or not, I have no idea. Although in all of my experience, I have learned to never assume anything. And I have seen many strange designs. One of them had an OP amp's output connected directly to ground. I was confused about that one until I chatted with the designer. Then it all made sense. -- Bill |
#18
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polarity of power cord - gateway fpd1520
JHC !!! Do you not understand the word "modern" ? Do you not understand the phrase "... deals with monitors of all types on a daily basis" ? I repair this stuff all day every day for a living. I have done for over 35 years. I cannot remember the last time I saw a piece of kit of any description, which employed a positive ground. My friend, who owns a computer repair shop, and has done for many years, cannot remember the last time - if ever - that he saw a monitor with an external power supply, that was not negative ground with the connector sleeve as the negative connection. With so much interconnectivity between household items now, there has had to be a degree of standardisation on this issue, and it has evolved through a general concensus amongst manufacturers, that negative ground will be the convention. As for your method of determining polarity, it makes no sense at all, unless you are assuming a series diode, which is quite unlikely in most modern kit, as it represents a waste of power due to its forward voltage drop. It may even have a shunt protection diode, in which case, your 'test' will ensure that the polarity is determined INcorrectly. Even if the device did have a series diode, depending on where the supply first goes, there is still no guarantee that there will be any reading at all on a standard multimeter on ohms. If there is not any diode - series or shunt - any reading of ohms obtained across the input socket, is unlikely to reveal anything meaningful. What is your experience in fault-finding, I wonder, to have caused you to have formulated such a bizarre method, and believe that it would uncategorically give you a correct result ? Arfa I've been working on this stuff for years as well, not as long as you, but I haven't been alive as long as you've been at it either. I've never seen a positive ground either, it would make no sense to do it that way. It's just standard that this stuff is negative ground, and that metal parts of the chassis are grounded for shielding, I've never once seen a case where this wasn't true so it's good enough for me. If one is still in doubt, pop the cover off and check the polarity of the filter lytics. |
#19
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polarity of power cord - gateway fpd1520
"BillW50" wrote in message . com... In , Arfa Daily typed on Sun, 30 Mar 2008 14:23:08 GMT: "BillW50" wrote in message . com... In , Arfa Daily typed on Fri, 28 Mar 2008 16:07:57 GMT: "BillW50" wrote in message . com... In , Arfa Daily typed on Fri, 28 Mar 2008 12:52:58 GMT: [...] As for a transistor radio that uses PNP transistors, I haven't seen one that uses transistors at all for many years, let alone PNP ones, so I think you might be struggling to fit that into my "modern" category, also. Well Arfa... they still use transistors (both NPN and PNP types) in modern equipment. The reason you don't see them anymore is do to the magic of minturization. But they are still there, just neatly packaged into what is known today as the intergrated circuit (IC chip). And I though I was pedantic !! Yes, of course ICs contain transistors, and yes, I would accept that some of them may be PNP types, depending on block function within the IC, but I don't think, with the best will in the world, that this is the level of transistor existence that William was referring to with his "transistor radio using PNP transistors" scenario. In any event, in the case of an IC taking a single polarity rail, it is irrelevant whether the transistors inside are NPN or PNP or FETs or whatever. PNP transistors are just used 'upside down', as are discrete PNP transistors when used in any piece of single polarity rail equipment. The ground is still (typically for //modern// equipment) the "-" side of the power supply / battery. Anyway, this is getting out of hand. The OP aked a simple question, and I gave a simple answer. This afternoon, I was in a friend's computer repair shop. Bear in mind that he deals with monitors of all types and makes on a daily basis. I asked him how he would go about determining the polarity of such a monitor, and he said that he would stick one side of his ohm meter on one of the D connector locking screws, and the other on each pin of the DC connector. When he found the pin that read short to the connector locking screw, it was his contention that he would have identified the "-" side of the power supply. So that's pretty much exactly what I said. He also frowned and shook his head, and said that he couldn't remember how many years it had been since he had seen a DC connector that had the pin as the "-". Which is also pretty much what I said ... Arfa That would be okay if it were a negative ground system. But like what William Sommerwerck mentioned, we don't know that. The way I would do it is to ohm the the power in. And the lower resistance would be the correct polarity. Although you would need another meter to read the polarity of the ohm meter. As they are not standardized on multimeters. You could also use a diode (or LED) to learn of the polarity of the meter as well. -- Bill JHC !!! Do you not understand the word "modern" ? Do you not understand the phrase "... deals with monitors of all types on a daily basis" ? I repair this stuff all day every day for a living. I have done for over 35 years. I cannot remember the last time I saw a piece of kit of any description, which employed a positive ground. My friend, who owns a computer repair shop, and has done for many years, cannot remember the last time - if ever - that he saw a monitor with an external power supply, that was not negative ground with the connector sleeve as the negative connection. With so much interconnectivity between household items now, there has had to be a degree of standardisation on this issue, and it has evolved through a general concensus amongst manufacturers, that negative ground will be the convention. As for your method of determining polarity, it makes no sense at all, unless you are assuming a series diode, which is quite unlikely in most modern kit, as it represents a waste of power due to its forward voltage drop. It may even have a shunt protection diode, in which case, your 'test' will ensure that the polarity is determined INcorrectly. Even if the device did have a series diode, depending on where the supply first goes, there is still no guarantee that there will be any reading at all on a standard multimeter on ohms. If there is not any diode - series or shunt - any reading of ohms obtained across the input socket, is unlikely to reveal anything meaningful. What is your experience in fault-finding, I wonder, to have caused you to have formulated such a bizarre method, and believe that it would uncategorically give you a correct result ? Arfa Actually being an electrical engineer for 35 years, I could careless how long your friend has been repairing computers. And the reason why the ohm meter works is because all of the curcuits are in parallel with the supply. Thus you will get a lower reading when the polarity is correct. And you will get a higher reading when it is not correct. Thus as all of the circuits are reversed biased. That is unmitigated nonsense. If there is a shunt protection diode, it will be FORWARD biased when the polarity is WRONG. Also, the fact that my friend repairs this stuff all day, and as an electrical engineer, you clearly do not, that makes him an expert, compared to you ... Whether or not all manufactures use negative ground or not, I have no idea. Well, as I repair this stuff all day as well, I *do* have an idea, so that clearly also makes me more of an expert on this particular subject, than you ... Although in all of my experience, I have learned to never assume anything. And I have seen many strange designs. One of them had an OP amp's output connected directly to ground. I was confused about that one until I chatted with the designer. Then it all made sense. -- Bill In general, I would agree with you not to assume anything, but some things are a matter of convention, and in recent years, based on my direct experience of such things, I would stick my neck on the line, and say that this is one, and that all modern kit, manufactured for the domestic market, employs circuitry with a negative ground, to which (most) external metalwork is firmly bonded. Arfa |
#20
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polarity of power cord - gateway fpd1520
Arfa Daily wrote:
snip JHC !!! Do you not understand the word "modern" ? Do you not understand the phrase "... deals with monitors of all types on a daily basis" ? I repair this stuff all day every day for a living. I have done for over 35 years. I cannot remember the last time I saw a piece of kit of any description, which employed a positive ground. My friend, who owns a computer repair shop, and has done for many years, cannot remember the last time - if ever - that he saw a monitor with an external power supply, that was not negative ground with the connector sleeve as the negative connection. With so much interconnectivity between household items now, there has had to be a degree of standardisation on this issue, and it has evolved through a general concensus amongst manufacturers, that negative ground will be the convention. snip I have resisted commenting but can do no longer; I don't know about the U.K., but I frequently encounter negative center coaxial power equipment in my work. These are not monitors, but a variety of consumer and industrial portable devices. When the connector is not labeled and I don't have docs, I will physically inspect the internal wiring or the pcb that hosts the power connector and also do resistance measurements between ground planes and the power connector contacts to determine ground. The assumption that ground planes are negative is a given in most instances. As for the subjective label "modern", that is a religious issue that shouldn't be a factor in good electronics practice Michael |
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